The present invention generally relates to medical devices used in diagnostic testing, which aid the advancement of intravascular catheters through blood vessels for performing interventional vascular diagnosis and treatment procedures. In particular, the present invention pertains to the use of a diagnostic sheath apparatus for facilitating atraumatic navigation of guide catheters along vascular pathways, thereby reducing the risk of causing trauma to the blood vessel, freeing plaque from the vessel wall, or creating emboli in the bloodstream. Additionally, the diagnostic sheath apparatus is capable of injecting contrast dye into the patient's vasculature to assist in the visualization of vascular pathways.
In recent years, a variety of noninvasive intravascular procedures have been developed for the diagnosis and treatment of atherosclerosis, featuring the localized restriction of blood flow through an artery due to the accumulation of atherosclerotic plaque along the artery wall. Most of these noninvasive procedures utilize intravascular catheters to aid the transport of medical devices through the patient's vasculature to reach the arterial blockage since the medical device is typically inserted into the body at a location that is a significant distance away from the treatment site. Once the catheter has been advanced into the desired position, the internal lumen of the catheter is utilized as a guiding sleeve through which various medical devices may be conveniently advanced to the diseased location of the patient's vessel for performing diagnostic or treatment procedures.
As an example, in the treatment of arteriosclerosis, procedures such as percutaneous transluminal coronary angioplasty (PTCA) may be used. In such case, a guide catheter is utilized to provide a conduit through which a dilatation balloon catheter device is conveniently advanced to reach the region of arterial stenosis. In typical coronary angioplasty procedures, the distal end of the guide catheter is introduced percutaneously into the patient's vasculature by way of the femoral artery. A guide catheter is advanced through the descending arteries and past the aortic arch, until the distal tip is properly located near the ostium of the coronary or peripheral artery. The proximal end of the guide catheter is then manipulated so that the distal end of the catheter is aligned with the lumen of a selected artery branching off from the aorta. Once the guide catheter is properly positioned, a guide wire and treatment device are advanced to the distal end of the guide catheter and then the guide wire is advanced into the obstructed artery until the distal tip of the wire extends beyond the stenotic region in the vessel. Thereafter, the treatment device, such as a dilatation balloon angioplasty catheter, a laser catheter, stent delivery system, or an atherectomy catheter is advanced over the guide wire until the distal end of the treatment device is positioned across the stenotic region in the coronary artery. The treatment device is then activated to reduce or remove the stenosis thereby reestablishing unimpeded blood flow through the artery.
Intravascular guide catheters are well known in the medical profession and generally consist of a somewhat flexible cylindrical catheter body having a proximal end and a distal end. In general, guide catheters are configured with an inner lumen extending through the catheter body from the proximal end to the distal end. The inner lumen provides a conduit though which various medical devices are advanced during noninvasive medical procedures. It will be appreciated that the inner diameter of the inner lumen must be sufficiently large as to receive and pass therethrough various treatment devices, such as dilatation catheters, atherectomy catheters, stent delivery systems, and the like. At the same time the outer diameter of the catheter body must be minimized to facilitate advancement of the catheter through vascular passageways. Therefore, the guide catheter body is generally constructed with a thin catheter wall which allows the inner diameter of the inner lumen to be maximized and at the same time provides a catheter body having a minimized outer diameter.
During intravascular treatment procedures, guide catheters must be able to traverse vascular pathways in an atraumatic manner to prevent injury to the patient. Atraumatic navigation along a blood vessel is often frustrated by the generally thin walled cylindrical construction of guide catheters. The hollow cylindrical construction of the catheter body includes an inner lumen having a relatively large inner diameter exposed at the distal end of the catheter. As the catheter is advanced along the vessel, the inner lumen of the catheter slides over the guide wire. As the guide catheter is advanced over the guide wire, the distal edge of the catheter is exposed and is likely to encounter vessel structure and/or plaque deposits along the way. When an obstacle is encountered the distal edges of the catheter embeds in the tissue and tissue matter is allowed to enter the hollow interior of the catheter. As deployment is continued, the distal edges of the catheter either embed into the tissue or flex and deflect away from the obstacle. Either way, the encounter between vessel tissue and the catheter increases the likelihood that tissue is dislodged into the blood stream, thus increasing the risk of embolism.
To reduce the likelihood of trauma to the soft lining of the blood vessels through which the catheter is routed, prior art catheters are configured with a deformable tip which is bonded to the distal end of the guide catheter. The deformable tip is generally a hollow cylinder formed from a polyurethane hybrid material having a lower durometer than the plastic comprising the remainder of the catheter. The soft tip may be adhesively bonded to the catheter and otherwise configured as a means to reduce the likelihood of trauma to the soft lining of the blood vessels.
A problem encountered with prior art catheter designs of this type is the limited bondable surface area between the thin wall catheter body and the deformable tip. Due to this limitation, the deformable tip may not be able to form a secure bond with the catheter body, leading to possibilities of separation of the deformable tip from the catheter body during use. Another problem with deformable tip catheters is the tendency of the soft deformable tip to buckle as the catheter encounters an obstruction during the advancement of the catheter along vessel which may lead to difficulties in controlling the navigation of the catheter device along the patient's vasculature.
In addition to assisting in the delivery of a guide catheter, during vascular therapy such as an angioplasty procedure or the stenting of a diseased area, it is highly desirable to be able to inject a contrast medium such as a radiopaque dye into the vessel upstream of the diseased site in order to check the flow past the site. This enables the physician to precisely locate the stenosis and assist in properly positioning the treatment device prior to treatment. After treatment, the injection of dye allows a determination to be made as to whether the procedure was successful or whether further treatment of the site, manipulation of the stent, or some other procedure is necessary.
Therefore, it is desirable for a diagnostic sheath catheter to provide a means for injecting radiopaque contrast dye, or the like, into the cardiovascular system to assist the visualization of occluded vascular pathways. In typical interventional angiography procedures, a catheter is advanced along the patient's vasculature while at the same time injecting contrast dye into the blood stream. The dye is then observed using flouroscopy techniques to visualize the patient's vascular pathways. During interventional procedures, the catheter is advanced along descending arteries until the distal tip of the catheter is properly located near the ostium of the artery. At the diseased location, additional contrast dye is then injected into the blood vessels to visualize occluded regions of the artery. Once the vascular obstruction has been identified, various treatment procedures may be performed to reduce or remove the arterial blockage, thereby reestablishing unimpeded blood flow through the artery.
Other intravascular devices have been described which purport to aid the advancement of catheters and allow for the injection of fluids into the bloodstream. One prior art method describes a telescoping guide catheter system having two single lumen guide catheters, wherein a first guide catheter slidably receives a second guide catheter. A working catheter may be passed through the inner lumen of the second guide catheter and fluids may be perfused between the inner lumen of the first guide catheter and the exterior of the second guide catheter. However, even distribution of injection dye fluid may be difficult to achieve.
Accordingly, what is needed and heretofore unavailable is a device which facilitates atraumatic navigation of intravascular guide catheters along the tortuous passageways of a patient's vasculature which minimizes or eliminates the problems associated with tip separation and is sufficiently stable in order to increase control during navigation. Additionally, the device must be adapted to receive a guide wire and be capable of consistently injecting contrast fluid into the bloodstream to assist in the visualization of vascular pathways. The present invention satisfies these and other needs.